Allison 6sp: Torque converter problem without codes?

[Trotorx2]

Im getting a noise/vibration that sounds like it is coming from the rear of the engine area when Im driving and increase the throttle just enough to pass someone...not a downshift or wot. I don't really understand how the torque converter does its thing so is it unlocking and vibrating then locking back up? No codes showing. Any other things it could be?
I need to get under the truck and look around.

 

[Righteyeblind]

Check your u-joints

 

[Trotorx2]

I'll have a look tomorrow thanks.

 

[JoshH]

How much horsepower are you running? Does it kind of sound like when you drive over the rumble strips on the side of the highway? What your describing sounds like the converter clutch slipping.

 

[Trotorx2]

Yes Josh, that's kinda what it sounds like. Wouldn't that throw a code?
I've been running the 120 hp tune except when I tow my tt then I use the tow tune. I haven't raced the truck just daily driving. I see a little better mpg with the 120 tune.

 

[Mike L.]

Usually if the cooverter clutch gets to the point where it chatters it will throw a P0741 code. Easy way to find out is to put a scanner on it and watch the TCC rpm slip while the vibration is occuring. Anything over 30-50 rpm slip is not acceptable.

 

[Trotorx2]

Thanks for the info Mike. Will this need to be checked with a Tech 2 or will a scan tool from say Actron work?

 

[Mike L.]

Thanks for the info Mike. Will this need to be checked with a Tech 2 or will a scan tool from say Actron work?

Must be a professional scanner with a data stream and not a code reader.

 

[Trotorx2]

Thanks again Mike :thumb:

 

[JoshH]

My truck did the same thing before I built the transmission, and it never threw a code. My dad's truck did it also without throwing a code.

 

[calabria69]

My truck did the same thing before I built the transmission, and it never threw a code. My dad's truck did it also without throwing a code.

X2, got a really bad vibration when in a higher gear....

 

[x MadMAX DIESEL]

from what I've seen in my own truck, the TC can slip for many miles before ever throwing a code.

 

[Mike L.]

from what I've seen in my own truck, the TC can slip for many miles before ever throwing a code.

I have seen that many times. That's why you use a scanner to check it.

 

[HEEPJEEP]

My TC was slipping REALLY BAD for probably 6 months. Never threw a CEL ever. When it first starting slipping it shuddered/vibrated. As it got worse it stopped the shuddering/vibrating slipped really bad when "locked"...and made tons of heat no matter what it was being commanded... I had the tranny flushed once at a shop, and flushed it myself 4 times (all within a few days). It made a difference (temperature wise, not slipping wise), but the tranny was already toast at that point. Flushing got me through a few more months driving really easy on it.

 

[Trotorx2]

I guess I need to go buy a scanner...and start lookin for funds for a trans upgrade

Mike did you ever put together your budget kit for the 6 speed? :hello:

 

[JoshH]

You can log converter slip with EFILive

 

[Trotorx2]

Yep Josh you can. I've been looking at this new AutoCal efilive is putting out. I think Trippin is selling them with tunes installed. :thumb: I don't want to have to learn how to tune...I like easy...plug and play!

 

[Trotorx2]

Ok, I'm bumping this because it did it again. I was in traffic on the hwy 65 mph behind some semi's holding up traffic. I accelerated without a down shift enought to get passed the semi's and I got the vibration I looked in the side mirror and the exhaust was blowing black smoke that stopped when the vibration stopped. I tried to get it to do it again but couldn't. I normally have to really get into the throttle to make it smoke like it did.
Now I'm confused. Why would a slipping TCC cause black smoke?

 

[LBZ_Baker98]

Ok, I'm bumping this because it did it again. I was in traffic on the hwy 65 mph behind some semi's holding up traffic. I accelerated without a down shift enought to get passed the semi's and I got the vibration I looked in the side mirror and the exhaust was blowing black smoke that stopped when the vibration stopped. I tried to get it to do it again but couldn't. I normally have to really get into the throttle to make it smoke like it did.
Now I'm confused. Why would a slipping TCC cause black smoke?

i know this is an old thread but did you ever figure out the issue?

 

[BoiseRob]

I just ordered a MikeL trans for my beast. She finally bit it. We think the torque converter is in full lockup since if I start the truck, as soon as the high-idle kicks in, it bogs down against the brakes and dies, If I put it in neutral, high idle works. Looking forward to my new trans. & AirDogII install.

Thanks Mike! :thumb: